Substrate coating apparatus

ABSTRACT

An apparatus is provided for coating a surface of a plate-like material, or substrate, specifically a semiconductor wafer, with a coating material. The apparatus includes a plurality of self-controlled removable modules including a coating assembly, at least one thermal conditioning module, and a substrate handling device, and a host controller. The coating assembly is used to dispense coating material from a coating source onto the surface of the substrate material positioned in the coating assembly. The material handling device is positioned to access and move substrates between the coating assembly, the at least one thermal conditioning module and other modules included in the apparatus. The host controller provides substrate thermal conditioning, coating and handling information to the corresponding modules and tracks the location of each substrate in the apparatus. In a preferred embodiment, each module has an individual controller that receives and executes treatment and handling instructions from the host controller. Preferably, the coating assembly and the at least one thermal conditioning module are arranged in opposing assemblies that define a middle portion therebetween in which the handling device is positioned. The opposing assemblies having outwardly opposing front and back faces which allows full access to the modules, from one or the other faces, and facilitates side-by-side arrangement of the apparatuses in a clean room.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an improved spin system layout andcontrol apparatus and methods for dispensing a process liquid onto asurface. More particularly, the present invention relates to improvedspin coating system for the placement of photoresist and developer on asemiconductor substrate wafer.

2. Description of the Invention Background

Integrated circuits are typically constructed by depositing a series ofindividual layers of predetermined materials on a wafer shapedsemiconductor substrate, or "wafer". The individual layers of theintegrated circuit are in turn produced by a series of manufacturingsteps. For example, in forming an individual circuit layer on a wafercontaining a previously formed circuit layer, an oxide, such as silicondioxide, is deposited over the previously formed circuit layer toprovide an insulating layer for the circuit. A pattern for the nextcircuit layer is then formed on the wafer using a radiation alterablematerial, known as photoresist. Photoresist materials are generallycomposed of a mixture of organic resins, sensitizers and solvents.Sensitizers are compounds, such as diazonapthaquinones, that undergo achemical change upon exposure to radiant energy, such as visible andultraviolet light resulting in an irradiated material having differingsalvation characteristics with respect to various solvents than thenonirradiated material. Resins are used to provide mechanical strengthto the photoresist and the solvents serve to lower the viscosity of thephotoresist so that it can be uniformly applied to the surface of thewafers. After a photoresist layer is applied to the wafer surface, thesolvents are evaporated and the photoresist layer is hardened, usuallyby heat treating the wafer. The photoresist layer is then selectivelyirradiated by placing a radiation opaque mask containing a transparentportion defining the pattern for the next circuit layer over thephotoresist layer and then exposing the photoresist layer to radiation.The photoresist layer is then exposed to a chemical, known as developer,in which either the irradiated or the nonirradiated photoresist issoluble and the photoresist is removed in the pattern defined by themask, selectively exposing portions of the underlying insulating layer.The exposed portions of the insulating layer are then selectivelyremoved using an etchant to expose corresponding sections of theunderlying circuit layer. The photoresist must be resistant to theetchant, so as to limit the attack of the etchant to only the exposedportions of the insulating layer. Alternatively, the exposed underlyinglayer(s) may be implanted with ions which do not penetrate thephotoresist layer thereby selectively penetrating only those portions ofthe underlying layer not covered by the photoresist. The remainingphotoresist is then stripped using either a solvent, or a strongoxidizer in the form of a liquid or a gas in the plasma state. The nextlayer is then deposited and the process is repeated until fabrication ofthe semiconductor device is complete.

The handling and treatment of the wafers must take place in a clean roomenvironment in order to prevent contamination of the layers. As aresult, a significant portion of the cost involved with the photoresistprocessing stages are associated with the cost of maintaining the cleanroom. Therefore, a reduction in the overall production cost of theintegrated circuit can be realized by reducing the amount of space, or"footprint", occupied by the equipment in the clean room. In addition,because all clean room activities must be shut down and an extensivecleanliness procedure followed after the performance of maintenance,further cost saving can be realized by minimizing the amount ofmaintenance time spent in the clean room.

Efforts in the prior art to date have focussed on minimizing floor spaceand increasing production capacity by integrating the resist processingsystem and automating the handling and treatment of the wafers using acentralized controller. One such system is disclosed in U.S. Pat. No.4,985,722 issued to Ushijima et al. and related U.S. Pat. Nos.5,177,514, 5,202,716 and 5,339,128. A problem that arises with the priorart integrated spin coating systems is that when the heating or coolingassemblies must be repaired or replaced, extensive and costly amounts ofdowntime occur because of the integration of the system. The costs areespecially significant in a clean room environment in which alloperations in the clean room have to be shut down until cleanliness canagain be achieved at a cost of thousands of dollars an hour. Anotherproblem that exists in the prior art is the amount of movement necessaryby the wafer handling device which will tend to generate particulatecontamination. In addition, because a path must be available for themovement of the wafer handler, this space is unavailable for other useand also will be unproductive during the portion of the process, inwhich the handling device is not located therein.

As such, the present invention is directed to modular process liquiddispense systems and methods using the same which overcome, amongothers, the above-discussed problems so as to provide a more easilycontrolled and maintained coating system having a smaller footprint foruse in resist processing of semiconductor wafers.

SUMMARY OF THE INVENTION

The above objects and others are accomplished by apparatuses and methodsin accordance with the present invention. The apparatus includes atleast one self-controlled treatment module, at least one treatmentmodule being a coating assembly capable of dispensing a coating materialfrom a coating source onto the surface of the plate-like materialpositioned in said coating assembly, at least one plate-like materialhandling device positioned to access the plate-like material, and tomove the material between the treatment modules and position thematerial in the treatment modules, and a host controller connected tothe treatment modules and the handling device. The host controllercontrols the handling device to provide for movement of the materialrelative to each treatment module, and controls the treatment module toperform a treatment on the material and tracks the plate-like materialin the apparatus. A preferred embodiment includes a plurality oftreatment modules and one handling device, each of which areself-controlled and receive treatment and handling instructions from thehost controller and the individual treatment and handling controllerscontrol the treatment and handling of the plate-like material. In thisway, the apparatus is thus highly modular and the individualcomplexities of the treatment and handling systems are concentrated inapplication specific controllers which can be readily monitored andwhich greatly simplifies the wiring and control systems needed in theapparatus.

Preferably, the treatment modules are arranged in two opposingassemblies that define a middle portion therebetween in which thehandling device is positioned. The opposing assemblies have outwardlyopposing faces to provide access to all of the treatment modules fromeither of the faces, which allows for the apparatuses to be arranged ina side-by-side manner in the clean room so as to minimize the amount offloor space required. In addition, the coating assembly and plate-likematerial loading platforms are provided in a first opposing assembly andall other treatment modules are provided in a second opposing assembly.This arrangement allows a significant portion of the second opposingassembly to be located outside of the clean room environment and alsoeliminates the need to occupy floor space to perform material loadingoperations, both of which further reduce the clean room space requiredto operate the machines.

Accordingly, the present invention provides for a highly modular systemthat minimizes the downtime required for maintenance and the amount ofclean room space occupied by the apparatus. In addition, the systemlayout provides for optimal utilization of the system components withoutincreasing the floor space of the apparatus. These advantages and otherswill become apparent from the following detailed description of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiment of the present invention will be described ingreater detail with reference to the accompanying drawings, wherein likemembers bear like reference numerals and wherein:

FIG. 1 is a perspective view of the present invention with a number ofenclosure panels removed;

FIG. 2 is a perspective view of a possible arrangement of a number ofapparatuses according to the present invention;

FIG. 3 is a front view of the back portion from the middle portion;

FIG. 4 is a rear view of the back portion looking from the plenum;

FIG. 5 is a network diagram showing a preferred embodiment of thepresent invention; and,

FIG. 6 is a top plan view of a possible layout of the present inventionin a clean room.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The operation of the apparatus 10 and methods will be describedgenerally with reference to the drawings for the purpose of illustratingpresent preferred embodiments of the invention only and not for purposesof limiting the same. The apparatus 10 of the present invention isuseful for coating a surface of a plate-like material and includes aplurality of treatment modules including thermal conditioning modules12, a spin coating, or dispense, assembly 14, and a robotic waferhandling assembly 16 for retrieving wafers 18 from a cassette 19 anddelivering the wafers 18 to various components according to handlinginstructions provided by a host controller 20. While the preferredembodiments will be described for convenience generally with respect touse of the apparatus 10 to apply photoresist to a wafer 18, personsskilled in the art will appreciate that the present invention is equallywell suited for use developing a photoresist coating on a wafer, andmore generally to applying any type of process liquid to a plate-likematerial.

The apparatus 10 is generally rectangularly shaped having a front 22, aback 24, sides 26, a top 28 and a bottom 29. In a preferred embodiment,a frame 30 is provided having a front portion 32, a middle portion 34and a back portion 36. The frame 30 is sized to support the thermalconditioning modules 12, the spin coating assembly 14 and the roboticwafer handling assembly 16. The front and back portions, 32 and 36,respectively, are two directly opposing assemblies having directlyopposing faces, 33 and 35, respectively, through which the plate-likematerial is placed into the treatment modules. The front portion 32, orfirst assembly, contains the spin coating assembly 14. The back portion36, or second assembly, contains the remaining treatment modulesincluding the thermal conditioning modules 12. The back portion 36 alsocontains a plurality of horizontal shelves 38 conditioning modules 12from the back 24 of the apparatus 10 and an electronics cabinet 40containing the host controller 20 is loaded above the shelves 38. Themiddle portion 34 includes a horizontal robot support shelf 42 disposedaround the wafer handling assembly 16 between the sides 26 and the frontand back portion, 32 and 36, respectively, of the frame 30. Preferably,all equipment and electronics not directly associated with treating thewafers 18 are positioned in the back portion 36 of the frame 30 so as tosegregate the components of the apparatus and optimize the amount ofequipment and electronics necessary in a clean room 37. In thisconfiguration, all of the treatment modules can be fully accessed fromthe outwardly opposing front and back faces 22 and 24 and from one ofthe opposing faces 33 and 35 defining the middle portion 34. This allowsthe apparatuses to be placed in a side-by-side arrangement with the backportion 36 extending outside of the clean room 37 into an externalplenum region 39 as shown in FIG. 6, thereby providing maintenanceaccess to the electronics from outside the clean room.

In addition, the top 28 of the apparatus 10 is substantially open toprovide access to remove the robotic wafer handling assembly 16 withouthaving to disturb the side-by-side arrangement of the apparatuses. Thelifting of the robotic wafer handling assembly 16 can be performed usinga portable counterbalanced crane assembly having a crane arm that can beextended beyond the base of the crane to lift the assembly or by anyconventional method. The bottom 29 of the apparatus 10 preferably has araised portion such that lift bars can be slid beneath the bottom 29 andthe apparatus can be lifted and moved using the bars, such as byemploying opposing portable wheeled jacks at each end of the liftingbars or by conventional methods.

In a preferred embodiment, the robotic wafer handling assembly 16includes a horizontally stationary, vertically actuating robot 50centered in the support shelf 42 having an actuating portion 52extending above the support shelf 42 and a stationary portion 54positioned below the support shelf 42. The actuating portion 52 includesat least one, preferably two, rotatable reciprocating end effectors, or"arms", 55 that can be reciprocated to insert and remove wafers 18 fromthe various components and a wafer mapping system (not shown) to scanthe cassette 19 with a laser/detector to determine the presence of thewafer 18 and the precise vertical location of the wafer 18. A robotcontroller 58 is slidably disposed through the back 24, rests onhorizontal shelves 38 below the plane of the support shelf 42 and isattached to the robot 50. In a preferred embodiment, an EquipeTechnologies, Inc. (Sunnyvale, Calif.) Model No. ATM-307-2-CSX robot isused with an Equipe Technologies controller Part No. ESC-100 ATM and amodel DD-50 laser/detector system manufactured by Hama Laboratories(Palo Alto, Calif.). However, any commercially available robots havingthe general characteristics described herein can be used in the presentinvention, including robotic handling assemblies 16 that do not containa dedicated controller, but are controlled by the host controller 20.

In a preferred embodiment, the robotic wafer handling assembly 16 alsoincludes wafer prealigner 60 that is slidably disposed through the back24 onto the shelving 38 above the support shelf 42 and is used to centerthe wafer 18 before the wafer 18 is put into the spin coating assembly14. An alignment controller 62 is attached to and controls theprealigner 60 and is connected to and receives alignment instructionsfrom the host controller 20. The alignment controller 62 is slidablydisposed through the back 24 onto the shelving 38 below the supportshelf 42 in the back portion 36. A commercially available waferprealigner 60, such as an Equipe Technologies PRE-201, and alignmentcontrollers 62, such as Equipe Technologies ESC-101, can be used withthe present invention. Alternatively, the prealigner 60 can be directlycontrolled from the host controller 20 or the robot controller 58 can beused to control the prealigner 60, in addition to the robot 50.

In a preferred embodiment, six thermal conditioning modules 12 includingthree heating, or bake, modules 70 and three cooling, or chill, modules72, are slidably disposed through the back 24 on shelves 38 divided intothree rows and two columns above the support shelf 42. The bake modulesare used to preheat the wafer in order to drive off water vapor from thesurface before spin coating photoresist material onto the surface of thewafer and also to bake the wafer following the application of thephotoresist in order to harden, or cure, the photoresist coating. Thechill modules 72 are used to cool the wafer 18 to process temperaturefollowing preheating and to lower the temperature of the wafer followingthe baking process. The total number of thermal conditioning modules 12,as well as the arrangement in terms of rows and columns, can beoptimized by the practitioner depending upon the processing speed of thespin coating assembly 14 and the capabilities of the robotic assemblyassembly 16. The thermal conditioning modules 12 are preferablyself-contained heating and cooling modules, 70 and 72, respectively,that contain individual controllers and can an act as stand alone units,if necessary, as described in the U.S. patent application Ser. No.08/667,704 entitled "Self-Contained Thermal Conditioning Apparatus",which is incorporated herein by reference. While it is preferred that aself-contained thermal conditioning module is used, other commerciallyavailable thermal conditioning modules can be used including thermalconditioning modules 12 that must be controlled by the host controller.

The spin dispense assembly 14 is positioned in the front portion 32 ofthe frame 30 in a spin station process enclosure 80 defined by frame 30.The enclosure includes a support table 82 on which various components ofthe spin dispense assembly 14 are seated, a back 84 through which thewafers 18 are loaded using the wafer handling assembly 16, a front door86 that provides an operator with access to the enclosure 80 and a top88. The enclosure 80 is a semi-isolated environment in that access islimited to a portion of the back 84 through which the wafers 18 areplaced into the spin assembly 14. An environmental control unit 90 thatis external to the apparatus 10 and outside the clean room environmentis used to control the air temperature and humidity level within theenclosure to specified process conditions and to provide a continuousair flow through the enclosure 80. The process air is plumbed throughthe back 24 of the apparatus 10 into the enclosure 80 through an airfilter 92, such as an ULPA filter manufactured by Filtra Corporation(Hawthorne, N.J.) Part No. 5020493103/4X21, and circulated through theenclosure 80. A humidity sensor 94, such as General Precision Inc.(Valencia, Calif.) Part Nos. 90109, 90110, 90125, is also included tomonitor and provide feedback control over the conditions of the processair within the enclosure 80.

The spin assembly 14 includes a process bowl 100 seated on the table 82and attached to a drain system (not shown) which extends through thesupport table 82 and is plumbed out through the back 24 or bottom 29 ofthe apparatus 10. A rotatable spindle chuck 102 is disposed within thebowl 100 and is connected by a shaft (not shown) to and rotated by aspindle 104 that is vertically actuated using a spindle lift axisactuator 106 through an opening in the bowl 100 and the support table82. Commercially available bowl, chuck and drain arrangements can beused with the present invention; however it is preferred that bowl andchuck arrangement be used such as that described in the U.S. patentapplication Ser. No. 08/667,784 entitled "Improved Spin Coating ProcessBowl", which is incorporated herein by reference.

The spindle 104 is used to spin the chuck 102 at predetermined speedusing a servo design motor to ramp up to speed and a phase-locked loopcontrol to maintain the revolutions per minute (RPM) to within aprescribed range. The spindle 104 contains water cooling lines to removeheat generated by the motor and the bearing and to control thetemperature of the spindle 104. The spindle 104 has a dedicated spindlecontroller 108 that is slidably disposed through the back 24 andpositioned in the back portion 36 and connected to the spindle 104 andhost controller 20. Commercially available spindles 104 and spindlecontrollers 108, such as MFM Technologies Inc. (Ronkonkoma, N.Y.) PartNos. BDC4000X-2678 and 18390, can be used in the present invention. Theactuator 106 is positioned in the front portion 32 of the frame 30beneath enclosure 80 and is preferably a serve controlled linear slidehaving programmable position control to provide precise control over themovement of the chuck 102. For example, an IAI America Inc. (Torrence,Calif.) Part No. 25-M-2-S-10-100-2 can be used in the present inventionin conjunction with an actuator controller 109, such as an Intelligentactuator manufactured by IAI America, which is positioned on shelves 38on the back portion 36 below table 42 and connected to the hostcontroller 20.

The spin assembly 14 further includes a dispense arm 110 that is movablypositioned on the support table 82 to dispense appropriate chemicalsonto the wafer 18 positioned on the chuck 102. The dispense arm 110 isplumbed out the back 24 of the apparatus 10 to a chemical supply source112 outside of the clean room which contains the chemicals for use inthe spin coating process. The chemicals are dispensed onto the wafer 18from dispense nozzles contained in the dispense arm 110 and the dispensenozzle are stored in a solvent bath 114 between spin coating processesto prevent the chemicals from drying out in the nozzles. Threedimensional movement of the dispense arm 110 is preferred to facilitatethe proper positioning of the dispense arm 110 to dispense the variouschemicals and can be accomplished using commercially available actuatingmechanisms for "theta" axis drive 116, "Y" axis drive 118, and "Z" axisdrive 120, such as from IAI America Inc. Model Nos. 12RS-80-360050-TS,IS-S-Y-M-8-60-300 and IS-S-X-M-80-60-100, respectively. The movement ofthe dispense arm 110 is also controlled by actuator controller 109.Preferably, the dispense arm 110 provides for temperature control ofcoating material, such as is described in the U.S. patent applicationSer. No. 08/667,784 entitled "Spin Coating Dispense Arm Assembly", whichis incorporated herein by reference. However, other dispense arms can beused in the present invention, such as are disclosed in U.S. Pat. No.5,429,912 issued to Biche et al. or commercially available dispense armassemblies.

A spin station controller 122 is provided to oversee the entire spincoating operation and is located in the electronics cabinet 40.Commercially available controllers can be used as the spin stationcontroller 122, such as a Model 4025A 486 Single Board Computer fromOctagon Systems Corp. (Westminster, Conn.). The spin station controller122 interfaces with the spindle controller 108, the actuator controller109, the environmental system 90, and the chemical supply source 112 andthe host controller 20 to coordinate the sequencing and timing of thespin coating operation.

In a preferred embodiment, two cassette loading platforms 126 arepositioned on the top 88 of the process enclosure 80 in the frontportion 32 of the frame 30. The platforms 126 are oriented such thatwhen the cassette 19 containing wafers 18 is placed on the platform 126,the wafers 18 can be removed by the robot arm 55. Preferably, a cassettesensor 128 is used to detect the presence of the cassette 19 and toprovide a signal to the host controller 20 indicating the presence orabsence of the cassette 19. While a current preferred embodimentincorporates two loading platforms 126, the preference is necessarilydictated by the selection of components to be used in any givenembodiment of the apparatus 10. For example, additional platforms couldbe provided above the two platforms, requiring only that the robotassembly 16 be capable of reciprocating to a level where the wafers 18can be removed from the cassette 19. The additional capacity describeddoes not require that the footprint of the apparatus 10 be increased,because the footprint is governed only by the desired capacity of theprocessing equipment used in the apparatus 10 and not the waferload/unload requirements as in the prior art.

The host controller 20 is contained in the electronics cabinet 40 andprovides high level control over all of the individual controllers inthe apparatus 10 and also over the chemical dispense and theenvironmental control systems as shown in the network diagram of FIG. 5.In a current preferred embodiment, the host controller 20 is a PentiumP90 industrial personal computer manufactured by Industrial ComputerSource (San Diego, Calif.); however, the choice of host controller 20will clearly depend on the particular application and the state of theprocessor art at the time. Operator control and monitoring of theapparatus 10 and host controller 20 is provided on the front 22 of theapparatus 10 to allow the operator to manually override and interruptcontrol of the entire process. A conventional host input/output anddisplay device 130 can be attached to the host controller 20 for use inthe present invention. The display 130 is preferably a flatpaneltouchscreen display, such as manufactured by Dolch Computer (Fremont,Calif.). It is also preferred that a similar host input/output displaydevice be remotely attachable to the back 24 (not shown) of theapparatus 10 to allow the operator to monitor the apparatus 10 fromoutside the clean room.

The host controller 20 is also preferably connected to a networkincluding user access locations 132, which provides oversight andcontrol access to production personnel, a database or recipe server 134,and a support equipment management server 136 that controls theenvironmental control system 90 and the chemical supply source 112, inaddition to coating material temperature controllers and pumps 137 and138, respectively. Because there is no need for this equipment to be inthe clean room, all of the above operations are controlled and performedexternally to the clean room and the process chemicals and system airare plumbed to the apparatus 10. Alternatively, the informationcontained in the recipe server 134 can be stored in memory attached tothe host controller 20.

Preferably, the wafers 18 in the cassette 19 are identified using a barcode. The bar codes are scanned, or read, by a bar code reader (notshown), such as a Symbol Technologies Inc. (Bohemia, N.Y.) ModelLS-3000-1000A, and the scanned information is passed to the hostcontroller 20, which accesses the processing instructions, or "recipe",for those particular wafers 18 from the system database 134. Theprocessing instructions provide the details of the particular process tobe performed on the wafers 18 in terms of a specific sequence ofhandling instructions and treatment instructions to be sent to thehandling device and treatment modules by the host controller 20. Forexample, in photoresist applications, such treatment informationincludes the coating materials to be applied, the solvents to be used,the temperature, amounts and dispense rates of the coating materials andsolvents, the heating and cooling temperatures and rates for the wafers,the wafer spin rates and times, the system temperature and exhaust airflow, etc.

In the operation of the present invention, the operator loads thecassette 19 containing wafers 18 to be processed onto the cassetteplatform 126. The cassette sensor 128 detects the presence of thecassette 19 and provides a signal to the host controller 20 indicatingthe presence of the cassette 19. The operator scans the bar codeassociated with the wafers using the bar code reader and the scannedcode is transmitted to the host controller 20. The host controller 20queries the system database 132 using the code to obtain the processinginstructions for the wafers 18 corresponding to the code.

After receiving the handling and treatment instructions, or recipe, thehost controller 20 transmits to the support equipment manager server 136instructions regarding 1) the chemicals to be used in the process, 2)the temperature of the chemicals, 3) the flow rate of the chemicals, and4) the system air temperature and exhaust flow rate. The supportequipment manager server 136 takes this information and distributes itto the chemical supply source 112, the fluid temperature controllers137, the chemical pumps 138 and the environmental control system 90,respectively.

The support equipment manager server 136 monitors the status of thechemical and environmental systems for compliance with the processinstructions and queues the host controller 20 when the processconditions have been attained prior to processing and if attainment ofthe processing conditions is lost during processing.

When the chemical and environmental systems have achieved the desiredprocessing conditions, the host controller 20 sends a signal to therobot controller 58 to scan the cassette 19 for wafers 18. The robotcontroller 58 activates the robot 50 to align the laser to be radiallypointing toward the center of the wafer 18 and slightly below the levelof the wafer 18. The robot controller 58 activates the laser andactuates the actuating portion 52 of the robot 50 vertically past thecassette 19 to record the vertical location of the wafers 18 in thecassette. This information is compared to the vertical location of theslots in the cassette stored in the robot controller 58 to determinewhich slots contain wafers 18. The host controller then directs therobot controller 58 to remove the first wafer 18 from the cassette 19and place the wafer 18 in the treatment module called for in the recipe.The robot controller 58 then directs the robot 50 to move the actuatingportion 52 to the precise level provided by the mapping system and thenfor the robot 50 to reciprocate arm 55 to reach into the cassette 19 andremove the wafer.

Assuming the wafer is present, the host controller 20 sends handlinginstructions to the robot controller 58 indicating the location of thefirst treatment module in which the wafer is to be processed. If, forexample, the first processing step is a preheating step to drivemoisture from the surface of the wafer, the host controller 20 alsosends thermal conditioning instructions signal to heating module 70providing the temperature and rate and duration of heating forprocessing the wafer. The robot 50 is directed by the robot controller58 to move the wafer from the cassette 19 to the heating module 70. Whenthe wafer has been placed into the heating module 70, the robotcontroller 58 informs the host controller 20 and the host controller 20directs the heating module 70 to perform the preheating operations usingthe operating instructions supplied by the host controller 20.Alternatively, the heating module 70 can be provided with a sensor todetect the presence of the wafer before executing the heatinginstructions provided by the host controller 20. While the preheatingoperations are taking place, the robot 50 can be directed by the hostcontroller 20 via the robot controller 58 to perform other operations.

At the completion of the preheating step, it may be necessary to coolthe wafer prior to apply the coating material In that case, the hostcontroller 20 provides handling instructions to the robot controller 58to remove the wafer from the location of the heating module 70 and movethe wafer a location in the cooling module 72. When the cooling module72 detects the presence of the wafer, the cooling module 72 performs thecooling operations using the thermal conditioning instructions suppliedby the host controller 20.

After the wafer has been cooled to the process temperature in thecooling module 72, it is generally necessary to align the wafer prior toapplying the coating material or developer to the wafer to ensure theprecise placement of the wafer in the spin coating assembly 14 and theproper dispensing of the coating material onto the wafer. The hostcontroller 20 sends handling instructions to the robot controller 58 toremove the wafer from the cooling module 72 and move the wafer into thewafer prealigner 60 and also sends alignment instructions to thealignment controller 62, which in turn controls the prealigner duringthe alignment of the wafer. Following the alignment, the host controller20 signal the robot 50 to remove the wafer from the prealigner. The hostcontroller 20 sends the instructions to the spin station controller 122to process the wafer 18 according to the recipe supplied by the hostcontroller 20. The spin station controller 122 then instructs theactuator controller 109 to move the spindle 104 to the wafer loadingposition and the actuator controller 109 prompts the spindle liftactuator 106 to lift the spindle 104. The spin station controller 122queues the environmental control system 90 to begin drawing a vacuumthrough the chuck 102. The host controller 20 instructs the robotcontroller 58 to place the wafer 18 on the chuck 102, which, in turn,instructs the robot 50 to place the wafer 18 on the chuck 102 and thewafer 18 held in place on the chuck 102 by the vacuum. The spin stationcontroller 122 then sends actuation instructions to the actuatorcontroller 109 to lower the spindle 104 to the process position in theprocess bowl 100 which are executed using the actuator 106. Theenvironmental control system 90 monitors the temperature and humidityconditions in the process enclosure 80 and signals the host controller20 if the system operating conditions fall out of specification. If theoperating conditions are in specification, the spin station controller122 runs the recipe by coordinating instructions to the spindlecontroller 108, the actuator controller 109, environmental system 90 andinput/output with the host controller 20 according to the timing andsequencing call for in the recipe.

For a typical recipe, the spin station controller 122 will instruct thespindle controller 108 to begin spinning the spindle and to movedispense arm 110 from a stored position in the solvent bath 114 to adispense position above the wafer in the process bowl 100 and theactuator controller 122 directs the theta, Y and Z drives, 116, 118, and120, respectively, to perform the movement. Once the dispense arm 110 isin position over the wafer, the spin station controller 122 directs thesupport equipment management server 136 to operate the chemical pumpsand 138 to deliver a prescribed amount of coating material at aprescribed rate through the dispense arm 110 to the wafer 18. Followingthe dispensing of the coating material onto the wafer, the spin stationcontroller 122 directs the actuator controller 109 to return thedispense arm 110 to the solvent bath 114 and directs the spindlecontroller 108 to stop the spinning of the chuck 102. After the spindle104 is stopped, the spin station controller 122 instructs the actuatorcontroller 109 to lift the chuck 102 to the loading position, afterwhich the environmental control system is instructed to release thevacuum. At that point, spin station controller 122 instructs the hostcontroller 20 that the process is completed. The host controller 20instructs the robot controller 58 to move the robot 50 into position andremove the wafer from the chuck 102. The host controller 20 directs therobot controller 58 to move the wafer into the heating module 70 andsends the heating module 70 thermal conditioning instructions providingthe temperature and heating rate and duration of the heat treatment.

Upon completion of the heating of the wafer, the host controller 20prompts the robot controller 58 to remove the wafer from the heatingmodule and place the wafer into the cooling module 72. The hostcontroller 20 provides temperature and cooling rate and durationinstructions, to the cooling module 72, after which the robot controller58 is prompted to remove the wafer from the cooling module 72 and placethe wafer back into the cassette 19.

The number of wafers that can be processed during a given time period bythe apparatus is invariably dependent upon the duration of theprocessing times of the various steps called for by the specific recipe.As should be apparent from the aforementioned example, the presentinvention provides an apparatus that has the flexibility to allow theprocessing of wafers to be performed in any sequence and withoutlimitations as to the steps that must be included. The apparatus 10embodies a higher architectural control level that allows the presentinvention to employ an integrated structure of autonomous distinctcomponents, which greatly simplifies system analysis, testing andcalibration and system layout. The high level of control allows theflexibility of the system to be exploited using relativelystraightforward processing algorithms or recipes. A further benefit ofthe modular apparatus is realized in a preferred system layout whichprovides access to all treatment modules from the front and back of theapparatus, thereby allowing the apparatuses to be closely packed in aclean room environment. In addition, the placement of the treatmentmodules, excluding the coating assembly, on one side of the apparatusallow a portion of the apparatus to be outside of the clean room,further reducing the size of the clean room, and also allowing thetreatment modules to be maintained from outside the clean room, furtherreducing maintenance downtime. While one embodiment of the presentinvention has been described incorporating distinct control structuresfor all of the system components, the present invention can beeffectively employed for use with systems in which completely distincthierarchical control may not be necessary or desirable. In those cases,the host controller, in addition to providing high level control ofthose components incorporating individual controllers, would providelower level direct control of other operations.

Those of ordinary skill in the art will appreciate that the presentinvention provides significant advantages over the prior art for processliquid dispense systems. In particular, the subject invention provides amore compacted apparatus for use in a clean room environment. Inaddition, the invention minimizes downtime for maintenance by providingstand alone component modules that can be maintained and replaced fromoutside the clean room and without extended shutdown for calibration.While the subject invention provides these and other advantages overother the prior art, it will be understood, however, that variouschanges in the details, materials and arrangements of parts which havebeen herein described and illustrated in order to explain the nature ofthe invention may be made by those skilled in the art within theprinciple and scope of the invention as expressed in the appendedclaims.

What is claimed is:
 1. An apparatus for coating a substrate surface withprocess liquid comprising:a plurality of self-controlled modulescomprisingat least one thermal conditioning module and a substratecoating assembly; and, a substrate handling device positioned to accesssaid coating assembly and said at least one thermal conditioning module;and, a host controller connected to said plurality of self-controlledmodules, wherein each of said plurality of self-controlled modules isremovable without disabling said other self-controlled modules or saidhost controller.
 2. The apparatus of claim 1, wherein said handlingdevice comprises:a horizontally stationary robot having at least onerotatable reciprocating end effector to access said at least one thermalconditioning module and said coating assembly; and, a robot controllerconnected between said robot and said host controller.
 3. The apparatusof claim 1, wherein said plurality of removable modules furthercomprises a substrate aligner.
 4. The apparatus of claim 3, wherein saidsubstrate aligner includesan alignment controller connected to said hostcontroller.
 5. The apparatus of claim 1, wherein said coating assemblycomprises:a process bowl having a bottom and an interior, and saidbottom contains an opening; a rotatable spindle movable in said openingin said bottom; a chuck disposed in said interior of said bowl andattached to said spindle, wherein said handling device can access saidchuck; a dispense arm positionable to dispense process liquid from asource toward said chuck; and, a spin station controller connectedbetween said host controller and said chuck and said dispense arm. 6.The apparatus of claim 5, wherein said coating assembly furthercomprises a spindle controller connected between said spindle and saidspin station controller.
 7. The apparatus of claim 6, wherein saidcoating assembly further comprises:an actuator attached to move saidspindle between a process position and a loading position; and, anactuator controller connected between said actuator and said spinstation controller.
 8. The apparatus of claim 7, wherein said actuatorcontroller is further connected to said dispense arm.
 9. The apparatusof claim 1, further comprising a recipe server containing substratethermal conditioning, coating and handling information and accessible bysaid host controller.
 10. The apparatus of claim 9, wherein saidsubstrate information is accessed using a code provided as input to saidhost controller.
 11. The apparatus of claim 10, further comprising a barcode scanner connected to said host controller.
 12. The apparatus ofclaim 1, further comprising:a support equipment server connected betweensaid host controller and said coating assembly; and, an environmentalcontrol system connected between said host controller and said coatingassembly.
 13. The apparatus of claim 1, further comprising a substrateloading platform included in one of said opposing assemblies andaccessible by said handling device.
 14. The apparatus of claim 13,wherein;said coating assembly and said substrate loading platform arearranged in a first assembly; and, said at least one thermalconditioning module is arranged in a second assembly opposing said firstassembly.
 15. The apparatus of claim 14, wherein:said opposingassemblies have outwardly opposing faces; and, said at least one thermalconditioning module and said coating assembly are removable from saidoutwardly opposing face of said second and first assemblies,respectively.
 16. The apparatus of claim 1, wherein said host controlleris connected provide substrate thermal conditioning coating, andhandling instructions to, and receive signals indicating the completionof said instructions from; said corresponding plurality ofself-controlled modules.
 17. The apparatus of claim 1, wherein each ofsaid plurality of self-controlled modules is operative as a stand alonemodule.
 18. An apparatus for coating a substrate surface with processliquid comprising:a plurality of self-controlled modules comprisingasubstrate coating assembly arranged in a first assembly, a plurality ofthermal conditioning modules arranged in a second assembly thatgenerally opposes said first assembly, said first and second assemblieshaving outwardly opposing faces, at least one substrate aligner disposedin said second assembly, wherein said coating assembly, and said thermalconditioning modules and said substrate aligner are removable throughsaid outwardly opposing face of said first and second assemblies,respectively, and a horizontally stationary substrate handling devicepositioned to access said self-controlled modules in said first andsecond assemblies and a substrate loading platform disposed in saidfirst assembly; and, a host controller connected to said plurality ofself-controlled modules, wherein each of said plurality ofself-controlled modules is removable without disabling said otherself-controlled modules or said host controller.